However, the jury, which was sent out to consider its decision on Wednesday, reached its verdict for Reich after a matter of hours and for Contogoulas this morning.

This is the second time both men had been in the dock. The pair stood trial for the same charges last summer but a jury could not reach a decision, even though it convicted three of their former colleagues.

Jay Merchant was sentenced to six-and-a-half years, Jonathan Mathew was jailed for four years, and Alex Pabon received two years and nine months. All worked at Barclays.

Another Barclays banker, Peter Johnson, who pleaded guilty, was jailed for four years.

"I would like to thank the jury for the swift and unanimous verdict that has cleared my name," a statement from Reich read. "For the last eight years I have consistently explained that I acted appropriately, honestly, and in accordance with the rules at the time. I am relieved and delighted to have been acquitted."

An SFO spokesperson said: "This Libor retrial concerns two of six individuals, four of whom were previously convicted. As prosecutors we proceed on the evidence and put our best case before a jury – we do not win every case."

Jonathan Pickworth, partner at law firm White & Case, said: "It is another lightning-quick acquittal following a lengthy trial, which tells us all we need to know about what the jury thought of the prosecution case."

Pickworth added: "No doubt there will be a post-mortem at the SFO. There is going to need to be a lot of thought about the merit of pursuing other benchmark trials".

The SFO is also bringing a prosecution of six individuals who deny manipulating Euribor, with the six due to stand trial in September.